1. Field of the Invention
The present invention relates to a door control device in which a door drive portion is constituted by an electric motor and a door is controlled to be opened and closed by driving force of the door drive portion.
2. Description of the Background Art
FIGS. 5A and 5B are views showing the configuration of a train door apparatus in which a door is driven by driving force generated by an electric motor. FIG. 5A shows the configuration of the train door apparatus 1 in a door open state. FIG. 5B shows the configuration of the train door apparatus 1 in a door full close state. FIG. 6 is a view for describing a general door open/close sequence which has been known in the background art.
As shown in FIGS. 5A and 5B, upon reception of an open request command/close request command from a now-shown train operating system, a door control device 2 controls a door drive portion built in the door control device 2 to achieve open/close control on the door apparatus in accordance with the door open/close sequence which has been known in the background art as shown in FIG. 6.
The train door driven by the door drive portion built in the door control device 2 is characterized by the existence of a lock mechanism 5 shown in FIG. 5A. In addition, when the door is locked by the lock mechanism 5 in the door full close state of FIG. 5B, the door (a left door panel 6 and a right door panel 7) can be kept in the full close state even if the driving force of the door drive portion (for example, a door drive motor) built in the door control device 2 is shut off. A position detector such as an encoder is built in the door control device 2. The state of the door is detected from an operation signal of the position detector, operation signals of door close detection switches 4 and operation information of a lock detection sensor (not shown) of the lock mechanism 5. In addition, the door close detection switches 4 detect a door close state when both a push rod 3 provided in an upper portion of the left door panel 6 and a push rod 3 provided in an upper portion of the right door panel 7 touch and push the door close detection switches 4 respectively. In addition, the lock detection sensor detects lock when the lock mechanism 5 operates to lock the door (the left door panel 6 and the right door panel 7).
As shown in FIG. 6, “Full Close” in Status (S1) is detected and determined on the condition of operation signals (Dcsm=ON) of the door close detection switches 4 in Event (E4a) “Dcsm=ON” shown in a center portion of FIG. 6 when the door is operated up to a full close position. In addition, “Open” in Status (S2) shown in a center upper portion of FIG. 6 performs an open operation in response to Event (E1) “Open Request Command” shown in an upper left portion of FIG. 6. In this manner, a continuous door open and close operation is achieved as an operation in the door open/close sequence which has been known in the background art. Incidentally, although not shown, Event (E1) “Open Request Command” is valid even during operation of “Close” in Status (S4) shown in a center portion of FIG. 6. In addition, Event (E3) “Close Request Command” shown in a center right portion of FIG. 6 is valid even during operation of “Open” in Status (S2) shown in the center upper portion of FIG. 6 and has a function to follow a command from the middle of the operation.
Event (E5a) “Obstruction Detected” shown in a center lower portion of FIG. 6 detects a state in which the door cannot be closed, for example, when a foreign substance is caught in the door. In this case, operation of “Recycle Open & Close” in Status (S5) in a center lower portion of FIG. 6 is performed. The operation of “Recycle Open & Close” in Status (S5) means a function of opening the door up to a full open state and resuming a close operation after a lapse of a predetermined time in order to remove the caught substance. It has been known by those skilled in the art that this function has been broadly used for train doors. Incidentally, various “Obstruction” detection methods may be used for the detection condition of Event (E5a) “Obstruction Detected”. For example, “Obstruction” may be detected when the door close detection switches 4 cannot detect a door close state though the position detector detects a state where the door position has been fixed to a position other than the full close position or a state where the door speed has been decreased, or when an overload state where a current flowing into the electric motor (motor) used for the door drive portion has increased beyond a predetermined value has been detected. However, the invention will make no mention about which “Obstruction” detection method to use.
JP-A-2003-020858 discloses a method for opening/closing a motor-operated switch. That is, JP-A-2003-020858 describes the method which includes: a first step of setting a timer in accordance with a movement distance toward a close direction or an open direction and starting an electric motor in the close direction or the open direction when a close switch or an open switch is turned ON in open/close control in a power window in a car etc.; and a second step of stopping the electric motor when pulses from a pulse generation unit are counted and reach a predetermined count value after the first step or when the time counted by the timer is up before the pulses reach the predetermined count value. Thus, abnormality of the motor-operated switch can be detected in an early stage and the overload state of the electric motor can be avoided. In addition, in the above description, the electric motor is rotated reversely when the time counted by the timer is up during operation of the electric motor.
It is believed that even the background-art door open/close sequence shown in FIG. 6 can operate the door apparatus normally. However, take into consideration whether sufficient safety is secured or not as a train door apparatus. In this case, for example, when obstruction occurs in the door close detection switches 4, Event (E4b) “Dcsm=OFF” is detected and the operation of “Close” in Status (S4) is executed again, as shown in FIG. 6. In this case, due to the obstruction in the door close detection switches 4, operation signals “Dcsm=ON” of the door close detection switches 4 indicated in Event (E4a) “Dcsm=ON” are not generated but the operation of “Recycle Open & Close” in Status (S5) is performed. As described above, under normal circumstances, the operation of “Recycle Open & Close” in Status (S5) is an operation to open the door up to a full open state and resume a close operation after a lapse of a predetermined time in order to remove a caught substance. Accordingly, it can be easily imagined that the operation of “Recycle Open & Close” in Status (S5) may be effective during the operation of “Close” when the train is stopped at a station etc. and the door side is on the platform side, but the operation of “Recycle Open & Close” can cause a serious accident when obstruction in the door close detection switches 4 occurs on the door side opposite to the platform side or during running of the train.
In addition, in the aforementioned method for the open/close control of the power window in JP-A-2003-020858, the motor-operated switch is suspended based on the time limit set by the timer as a safety measure during trouble of the sensor. Therefore, when this method is applied to a train door, the train may run with the door open. Accordingly, there is a problem that the method cannot be used for taking a sufficient safety measure.